Multiple-level X-ray analysis for determining fat percentage

Abstract

A method and apparatus is provided for determining in a non-destructive manner the quantities of components in a material having irregular surfaces and which may be of a non-uniform size and of a variable consistency. Three or more beams of polychromatic X-rays, each at a different level of energy, are passed through the material, and the measurements of each incident beam and each transmitted beam are utilized in determining the percentage of one or more of the components after having substantially eliminated so-called beam-hardening effects which otherwise limit the utility of polychromatic beams.

I claim: 
     
       1. An apparatus for determining the quantitative relationship of components in an item composed primarily of two components varying from each other in molecular makeup, the apparatus being capable of analyzing items variable in surface roughness, weight, density, thickness, and overall geometrical configuration comprising: means for generating a first incident beam of polychromatic X-ray radiation at a first preselected tube excitation potential and for directing it toward an item composed primarily of two components,   means for generating a second incident beam of polychromatic X-ray radiation at a second preselected tube excitation potential and for directing it toward said item;   means for generating a third incident beam of polychromatic X-ray radiation at a third preselected tube excitation potential and for directing it toward said item to combine with the first and second beams to provide inputs useful in substantially eliminating, while determining the quantitative relationship of the components, effects of inaccuracies that are introduced by surface roughness of items;   means for monitoring, detecting and measuring intensity values of each of the beams after they pass through said item;   means for determining calibration values at each of said preselected tube excitation potentials; and   a means for processing said intensity values measured for the item together with the calibration values for automatically and accurately calculating the percentage of one of said components of the item irrespective of surface roughness of the item and the polychromatic nature of said three generating means.   
     
     
       2. The apparatus of claim 1, wherein said polychromatic radiation generating means includes a high voltage generator, an X-ray tube, and a control means for variably activating the generator between at least said three preselected tube excitation potentials. 
     
     
       3. The apparatus of claim 1, further comprising a beam monitor ionization means in association with the means for generating incident beams of polychromatic radiation, said beam monitor ionization means being for simultaneous cooperation with said incident beams generating means to detect fluctuations in intensity of the incident beams. 
     
     
       4. The apparatus of claim 1, further comprising an electronic data processing subsystem including said means for determining calibration values and said means for processing the intensity values and calibration values. 
     
     
       5. The apparatus of claim 1, further comprising a filtering means between said means for generating polychromatic radiation and said means for measuring the intensity of the beams after they pass through said item. 
     
     
       6. The apparatus of claim 1, further comprising means for generating a fourth incident beam of polychromatic X-ray radiation at a fourth tube excitation potential and for directing it toward said item. 
     
     
       7. The apparatus of claim 1, wherein said item is meat, one of said two components is fat, and said apparatus precludes any need to smooth a surface of said meat item. 
     
     
       8. The apparatus of claim 1, further including means for passing a plurality of said items to and away from said radiation generating means. 
     
     
       9. A method for determining the quantitative relationship of components in an item composed primarily of two components varying from each other in molecular makeup the method being capable of analyzing items variable in surface roughness, weight, density, thickness, and overall geometrical configuration comprising: selecting a primarily 2-component item;   transmitting an incident beam of polychromatic X-ray radiation at a first preselected energy level through the item to develop an attenuated first beam;   transmitting a second incident beam of polychromatic X-ray radiation at a second preselected energy level through the item to develop an attenuated second beam;   transmitting a third incident beam of polychromatic X-ray radiation at a third preselected energy level through the item to develop an attenuated third beam;   measuring the intensity of each of the beams attenuated by said item;   calibrating said measured intensity of the incident beams and attenuated beams by using calibration constants of a set of calibration standards; and   quantifying the relationship of the components in the item, said quantifying step including combining said three transmitting steps, said measuring step and said calibrating step to substantially eliminate effects of inaccuracies that are introduced by surface roughness of times and by polychromatic nature of said three beams.   
     
     
       10. The method of claim 9, wherein the lowest of said tube excitation potentials is not less than 20 KeVp. 
     
     
       11. The method of claim 9, wherein said item is meat and one of said two components is fat, and wherein said method includes precluding any need to smooth a surface of said meat item. 
     
     
       12. The method of claim 9, further comprising monitoring the incident beams to account for fluctuations in the incident beams. 
     
     
       13. The method of claim 9, wherein said calibrating step includes obtaining calibration standards attenuated beam readings by passing said first, second and third incident beams through said set of calibration standards, and calculating calibration constants for said item at each of said tube excitation potentials by correlating the respective intensity of each of said beams attenuated by said item with said calibration standards attenuated beam readings, respectively. 
     
     
       14. The method of claim 9, further comprising computing apparent component percentages by assuming that the item selected has smooth surfaces, and adjusting said apparent component percentages in conjunction with said calibrating step. 
     
     
       15. The method of claim 9, wherein said calibration standards are sandwiches of two materials having different molecular weights. 
     
     
       16. The method of claim 9, further comprising transmitting a fourth incident beam of polychromatic X-ray radiation at a fourth preselected tube excitation potential through the item to develop an attenuated fourth beam. 
     
     
       17. The method of claim 9, wherein the highest of said tube excitation potentials is not more than 120 KeVp. 
     
     
       18. The method of claim 9, wherein said selecting step includes choosing a plurality of said items that are analyzed in a generally continuous stream.